Chemsheets AS006 (Electron arrangement) 17/11/2018 www.CHEMSHEETS.co.uk PERIODICITY © www.chemsheets.co.uk AS 1055 3-July-2015

The orbitals that the highest energy electrons are in s block p block d block The orbitals that the highest energy electrons are in © www.chemsheets.co.uk AS 1055 3-July-2015

Calcium 20 e- 1s2 2s2 2p6 3s2 3p6 4s2 s block p block d block The orbitals that the highest energy electrons are in © www.chemsheets.co.uk AS 1055 3-July-2015

Iron 26 e- 1s2 2s2 2p6 3s2 3p6 4s2 3d6 d block Fe s block p block d block The orbitals that the highest energy electrons are in © www.chemsheets.co.uk AS 1055 3-July-2015

Chlorine 17 e- 1s2 2s2 2p5 p block Cl s block p block d block The orbitals that the highest energy electrons are in © www.chemsheets.co.uk AS 1055 3-July-2015

Helium 2 e- 1s2 s block He s block p block d block The orbitals that the highest energy electrons are in © www.chemsheets.co.uk AS 1055 3-July-2015

ATOMIC RADIUS From: http://2012books.lardbucket.org/books/beginning-chemistry/s12-05-periodic-trends.html

ATOMIC RADIUS © www.chemsheets.co.uk AS 1055 3-July-2015

ATOMIC RADIUS Across a period: outer electrons are in same shell more protons in nucleus same amount of shielding so stronger attraction between nucleus and outer shell electrons so outer shell electrons pulled closer to nucleus Na Mg Al Si P S Cl © www.chemsheets.co.uk AS 1055 3-July-2015

1st IONISATION ENERGY © www.chemsheets.co.uk AS 1055 3-July-2015

1st IONISATION ENERGY General trend across period more protons atoms get smaller therefore stronger attraction from nucleus to electron in outer shell © www.chemsheets.co.uk AS 1055 3-July-2015

1st IONISATION ENERGY Group 2 → 3 electron lost from: Group 3 = p orbital Group 2 = s orbital p orbital is higher energy than s orbital, so easier to lose electron. © www.chemsheets.co.uk AS 1055 3-July-2015

1st IONISATION ENERGY Group 5 → 6 Group 6 element loses electron from orbital with 2 electrons (p4 ). Group 5 element loses electron from orbital with 1 electron (p3 ). Extra electron-electron repulsions make it easier to lose electron from p4 than p3. © www.chemsheets.co.uk AS 1055 3-July-2015

ELECTRONEGATIVITY H 2.1 He Li 1.0 Be 1.5 B 2.0 C 2.5 N 3.0 O 3.5 F 4.0 Ne Na 0.9 Mg 1.2 Al Si 1.8 P S Cl Ar K 0.8 Ca Sc 1.3 Ti V 1.6 Cr Mn Fe Co Ni Cu 1.9 Zn Ga Ge As Se 2.4 Br 2.8 Kr Rb Sr Y Zr 1.4 Nb Mo Tc Ru 2.2 Rh Pd Ag Cd 1.7 In Sn Sb Te I Xe Cs 0.7 Ba La 1.1 Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn Power of an atom to attract the 2 electrons in a covalent bond

ELECTRONEGATIVITY Power of an atom to attract the 2 electrons in a covalent bond © www.chemsheets.co.uk AS 1055 3-July-2015

ELECTRONEGATIVITY Across a period: more protons in nucleus Power of an atom to attract the 2 electrons in a covalent bond Across a period: more protons in nucleus smaller atomic radius so stronger attraction between nucleus and 2 electrons in covalent bond © www.chemsheets.co.uk AS 1055 3-July-2015

MELTING & BOILING POINTS © www.chemsheets.co.uk AS 1055 3-July-2015

MELTING & BOILING POINTS Na metallic Mg metallic Al metallic Si giant covalent P4 simple molecular S8 simple molecular Cl2 simple molecular Ar monatomic Strong attraction between metal ions and delocalised electrons Al > Mg > Na as higher charge more delocalised electrons smaller ions © www.chemsheets.co.uk AS 1055 3-July-2015

Sodium (Na) Mpt 98ºC Magnesium (Mg) Mpt 650ºC + e- + + + e- e- e- e- e- 2+ e- 2+ 2+ e- 2+ e- e- e- e- e- e- e- + + + e- 2+ e- 2+ e- e- 2+ e- e- e- e- e- 2+ 2+ 2+ e- 2+ + + e- + + e- e- e- e- e- e- e- 2+ 2+ 2+ e- e- + + + Sodium (Na) Mpt 98ºC Magnesium (Mg) Mpt 650ºC

MELTING & BOILING POINTS Na metallic Mg metallic Al metallic Si giant covalent P4 simple molecular S8 simple molecular Cl2 simple molecular Ar monatomic Strong attraction between metal ions and delocalised electrons Al > Mg > Na as higher charge more delocalised electrons smaller ions Have to break many strong covalent bonds Weak van der Waals’ forces between molecules S8 > P4 > Cl2 (bigger molecules, more electrons, more vdW) Very weak van der Waals’ forces between atoms © www.chemsheets.co.uk AS 1055 3-July-2015